Explosions rang out and huge plumes of smoke rose into the sky, which could be seen from across the city.

The blaze broke out just before 7pm on Thursday.

Fire crews were scaled back at 11pm, with the last crews finally leaving the site by 1am.

Roughly 50 firefighters attended the incident.

Smoke could be seen for miles (Image: James Norris)

The aftermath of the fire today

Five boys, one aged 15, three aged 16, and one aged 19, have been arrested today on suspicion of arson and are currently in custody at Thorpe Wood Police Station.

John Peach, 60, a former city councillor and mayor of Peterborough, and the former deputy chairman of Cambridgeshire and Peterborough’s fire authority, told Cambridgeshire Live last night that he saw the managing director trying to get in.

He said: "He was getting quite upset. He’s asked can I get in, and they’ve told him no.

"I heard the explosion.

"It appears to be in their vehicle compound that the fire started after just looking at the site.

"I was at Belsize Avenue and it was the far side of the site, and that’s where it was. It sounded like fuel tanks going off."

Five teenagers are being held by police

The cause of the fire remains under investigation (Image: @KaelaDePaola /Twitter)

Speaking last night, a Whirlpool spokesman said: "Officers from Cambridgeshire Constabulary have been investigating the scene throughout today and we have now been informed that police suspect arson to be the cause of the fire.

"We are deeply concerned by this development and are assisting the police in every way we can as they continue their investigations.

"We urge anyone with any information that might assist the police investigation to contact Cambridgeshire Constabulary.

"Whirlpool would like to extend its most sincere thanks to all the emergency services who attended and assisted in tackling this incident, including police, fire, and ambulance crews.

"Whirlpool also apologises to people living and working in the area for any disruption caused."